Several methods for displaying a 3-dimensional image in conventional display devices are currently known in the art. One of such methods is a stereoscopic display method, which provides a depth perception of 3-dimensional display from a 2-dimensional screen. The stereoscopic display method uses an image parallax between left and right images to provide the depth perception at the 2-dimensional screen. However, since parallax information may be changed only by a pixel unit according to the resolutions of a camera for obtaining the image and a display device, it is difficult to express minute changes in the parallax information within one pixel. Thus, there is a limitation in reducing the minimum unit of depth variation, which may be expressed through the parallax information.
Another method of 3-dimensional image display is a depth fused 3D (DFD) display method, which shows a plurality of 2-dimensional images overlapped with each other by arranging a plurality of displays back and forth. The DFD display method controls the depth perception of the 3-dimensional image through changing the brightness ratio of, for example, two 2-dimensional images on two respective displays arranged back and forth. This method can express minute changes in the parallax information by utilizing two flat panel display devices to implement a 3-dimensional image. However, the DFD method has some problems in that the presentable depth is limited within the gap between the two display devices and the size of the entire device is too large due to the physical distance between the two display devices.